The shift from traditional wooden cross-arms to pultruded glass fiber-reinforced polymer (pGFRP) composites is reshaping the structural integrity of high voltage transmission towers. A recent study, conducted at the Faculty of Engineering, Universiti Putra Malaysia, explores the mechanical deformation and flexural creep characteristics of these two materials under operational loads.
The research presents compelling arguments for replacing wood with pGFRP, primarily due to its superior performance. According to the study, "pGFRP cross-arms showed lower deflection at working loads compared to Balau wood." The findings indicate pGFRP displayed 32% less deflection under normal operational conditions, maintaining structural integrity more effectively than its wooden counterparts.
Wooden cross-arms, commonly made from Balau wood, have historically been used due to their natural strength and ease of availability. Yet, the study notes substantial limitations: aging wood often fails to meet longevity demands, with service lives rarely surpassing 14 years. With the introduction of pGFRP to the Malaysian market around 1999, researchers focused on exploring materials with enhanced durability, reduced weight, and structural viability.
The methodology employed involved load testing of the cross-arms installed on 132 kV towers. Each cross-arm was subjected to real-world conditions, simulating the forces exerted by transmission wires during both normal operation and possible fiascoes like broken wire scenarios. The load-deflection relationships were analyzed using finite element analysis (FEA) alongside practical tests.
The results highlighted the significant advantage of pGFRP, particularly under sustained loading. The study confirmed, “The creep strength of wood was 34% lower than of pGFRP cross-arms,” indicating pGFRP's enhanced ability to withstand long-term stress. This is particularly relevant as cross-arms are routinely exposed to environmental factors leading to rapid degradation.
Although pGFRP demonstrated superior characteristics, the study did identify specific load points requiring reinforcement strategies for optimal performance, especially under the most stressful conditions. Key areas, such as Point Y3, where maximum loads are observed, were noted as focal points for future structural enhancements.
Despite wood's notable flexural properties, the investigation outlines how pGFRP behaves more predictably under stress, marking it as the more reliable choice for the demanding conditions faced by transmission structures. The researchers concluded, “The investigation serves as a foundational framework for future research endeavors,” emphasizing the road ahead for improving and innovatively applying these advanced materials.
Moving forward, industry standards may see adjustments as the advantages of composite materials like pGFRP become undeniable. With greater longevity, reduced maintenance costs, and enhanced structural reliability, the potential societal benefits are clear – ensuring the safety and resilience of power transmission systems across Malaysia and beyond.